GDNSD-PLUGIN-METAFO(8) gdnsd GDNSD-PLUGIN-METAFO(8)NAMEgdnsd-plugin-metafo - gdnsd plugin for address meta-failover
SYNOPSIS
Minimal example gdnsd config file using this plugin:
plugins => {
metafo => {
resources => {
prod_www => {
datacenters => [ dc-01, dc-02, dc-03 ]
dcmap => {
dc-01 => 192.0.2.1
dc-02 => { lb01 => 192.0.2.2, lb02 => 192.0.2.3 }
dc-03 => [ 192.0.2.4, 192.0.2.5, 192.0.2.6 ]
}
}
}
}
}
Example zonefile RRs:
www 600 DYNA metafo!prod_www
www-dc01 600 DYNA metafo!prod_www/dc-01
DESCRIPTIONgdnsd-plugin-metafo is a meta-plugin. It does static-ordered address
failover between multiple "datacenters" (which may or may not
correspond with real datacenters, it's just a convenient label). Each
datacenter is defined in terms of other plugins such as "multifo",
"weighted", etc, as described below.
CONFIGURATION - TOP-LEVEL
The top level of the metafo plugin's configuration (i.e. "plugins => {
metafo => { ... } }") supports only one fixed, required key,
"resources", whose value must be a hash. The contents of "resources"
is a key per named resource, with the value defining that resource.
Any other keys present at the top level will be inherited down inside
of each per-resource hash inside the "resources" stanza, acting as per-
resource defaults for anything not defined explicitly there, as
explained below.
CONFIGURATION - RESOURCES
All keys within the resources stanza represent named resources, which
can be referenced by "DYNA" RRs in zonefiles (e.g. "www DYNA
metafo!resource_name"). Each resource's value must be a key-value hash
configuring the resource itself. Lightweight structural example:
plugins => {
metafo => {
resources => { resA => { ... }, resB => { ... } }
}
}
Within a resource, there are only two specifically meaningful keys:
"datacenters = [ A, B, C, ... ]"
Array of datacenter names, required. This is the set of datacenter
name labels used for this resource, in the order they will be
checked for failover.
"dcmap = { ... }"
Hash, required. The "dcmap" is a key-value hash where the keys
must be exactly the list of datacenters defined in this resource's
"datacenters" list, and the values defined the address
configuration of each datacenter. Another minimal structural
example down to this level:
plugins => {
metafo => {
resources => {
resA => {
datacenters => [ dc01, dc02 ],
dcmap => {
dc01 => ???
dc02 => ???
}
}
}
}
}
There are several forms the per-datacenter values ("???" above) can
take, documented in the next section.
Any keys other than "datacenters" and "dcmap" at the per-resource level
serve as inherited defaults for each per-datacenter configuration
inside of the "dcmap".
PER-DATACENTER RESOLUTION
The value of the datacenters within the "dcmap" section of a resource
can take several forms. It is important to understand that for the
most part, plugin_metafo does not deal with this level of results
itself, but instead delegates the work at this scope to other plugins.
The most direct and obvious way to do this is with a direct reference
of the form "%plugin!resource", as shown here:
plugins => {
metafo => {
resources => {
resA => {
datacenters => [ dc1, dc2 ],
dcmap => {
dc1 => %multifo!res_mfo1
dc2 => %multifo!res_mfo2
}
}
}
}
multifo => {
res_mfo1 => { lb01 => 192.0.2.1, lb02 => 192.0.2.3 }
res_mfo2 => { lb01 => 192.0.2.111, lb02 => 192.0.2.113 }
}
}
However, to make life simpler in the simple cases, plugin_metafo can
synthesize the lower-level plugin's configuration from a hash, like so:
plugins => {
metafo => {
resources => {
resA => {
datacenters => [ dc1, dc2 ],
dcmap => {
dc1 => { plugin => multifo, lb01 => 192.0.2.1, lb02 => 192.0.2.3 }
dc2 => { lb01 => 192.0.2.111, lb02 => 192.0.2.113 }
# the above are effectively treated as:
# dc1 => %multifo!metafo_resA_dc1
# dc2 => %multifo!metafo_resA_dc2
}
}
}
}
# below does not exist in your configfile, but is what plugin_metafo
# synthesizes to support the above:
#multifo => {
# metafo_resA_dc1 => { lb01 => 192.0.2.1, lb02 => 192.0.2.3 }
# metafo_resA_dc2 => { lb01 => 192.0.2.111, lb02 => 192.0.2.113 }
#}
}
Within a hash like the above, the special key "plugin" will be stripped
out internally and used to name the plugin we synthesize the config
for. "plugin" defaults to "multifo" if not specified. Note that
"plugin" could also be specified at the resource level (just inside of
the "resA" stanza) to change the default for all "dcmap" entries in one
resource, and could also be specified at the outer-most scope (just
inside the "metafo" stanza) to change the default for all resources.
The defaulted-down "plugin" is also the default for the direct-
reference "%plugin!resource" form discussed earlier. With the correct
default plugin name, it can be shortened to just "!resource".
The same sort of key-value inheritance scheme (top-level -> per-
resource level -> per-datacenter level) can also be used for any other
parameter in synthesized resource configurations specific to the per-
datacenter plugin(s) you are using. A common example would be the
"service_types" parameter that most plugins which support monitored
address results have. Note that these other values (e.g.
service_types) would only apply to synthesized resources, not to
direct-references like "%multifo!foo", which must be configured
entirely separately within that plugin's config.
There are two other possible shortcut values for datacenters: a single
direct address, or an array of addresses. If a single IP address or an
array of IP addresses are specified, plugin_metafo will synthesize a
hash from them with the plugin forced to "multifo" (since it cannot
know the syntax of hashes for all other plugins, which may differ), and
give them address labels 1, 2, etc.
A much more complete example, showing off most of the features above:
plugins => {
metafo => {
plugin => multifo # change default for all resources
service_types => [ bar ] # default service_types for synthesized below
resources => {
resA => {
plugin => multifo # change default for this resource
service_types => [foo, bar] # services types for synthesized below:
datacenters => [ dc1, dc2, dc3, dc4, dc5, dc6, dc7 ],
dcmap => {
dc1 => { plugin => multifo, lb01 => 192.0.2.1, lb02 => 192.0.2.3 }
dc2 => { lb01 => 192.0.2.111, lb02 => 192.0.2.113 }
dc3 => %simplefo!foo
dc4 => { plugin => simplefo, primary => 192.0.2.100, secondary => 192.0.2.101 }
dc5 => !bar
dc6 => 192.0.2.150
dc7 => [ 192.0.2.180, 192.0.2.181 ]
}
}
}
}
# below, commented-out sections show configuration synthesized
# by plugin_metafo, whereas the rest are direct-references that
# had to be manually specified here:
multifo => {
# metafo_resA_dc1 => { lb01 => 192.0.2.1, lb02 => 192.0.2.3, service_types => [foo, bar] }
# metafo_resA_dc2 => { lb01 => 192.0.2.111, lb02 => 192.0.2.113, service_types => [foo, bar] }
bar => { asd => 192.0.2.77, xyz => 192.0.2.88 }
# metafo_resA_dc6 => { 1 => 192.0.2.150, service_types => [foo, bar] }
# metafo_resA_dc7 => { 1 => 192.0.2.180, 2 => 192.0.2.181, service_types => [foo, bar] }
}
simplefo => {
foo => { primary => 192.0.2.80, secondary => 192.0.2.81 }
# metafo_resA_dc4 => { primary => 192.0.2.100, secondary => 192.0.2.101, service_types => [foo, bar] }
}
}
Note in the example above that "%multifo!bar" and "%simplefo!foo" would
have had their default "service_types = default" rather than the one
specified at the metafo level, because they were not synthesized. It
would be up to you to keep all of the service_types in sync when using
direct references.
SYNTHETIC PER-DATACENTER RESOURCES
This plugin will synthesize additional, per-datacenter resource names
from your configuration. They are named as "resname/dcname". For
example, if you define a metafo resource named "prodwww" with the
datacenter list "[ pri, sec ]", the resource names "prodwww/pri" and
"prodwww/sec" will be sythesized and can be used in zonefile records,
e.g.:
www-backup 300 DYNA metafo!prodwww/sec
When used, these per-datacenter synthetic resource names cause a given
lookup to skip the normal failover process and directly return results
from that particular datacenter.
SEE ALSOgdnsd.config(5), gdnsd.zonefile(5), gdnsd(8)
The gdnsd manual.
COPYRIGHT AND LICENSE
Copyright (c) 2012 Brandon L Black <blblack@gmail.com>
This file is part of gdnsd.
gdnsd is free software: you can redistribute it and/or modify it under
the terms of the GNU General Public License as published by the Free
Software Foundation, either version 3 of the License, or (at your
option) any later version.
gdnsd is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
for more details.
You should have received a copy of the GNU General Public License along
with gdnsd. If not, see <http://www.gnu.org/licenses/>.
gdnsd 1.11.4 2014-07-18 GDNSD-PLUGIN-METAFO(8)
